1. Field of the Invention
The present invention relates to a fluid treatment device. More particularly, in its preferred embodiment, the present invention relates to an ultraviolet radiation water treatment device.
2. Description of the Prior Art
Fluid treatment devices and systems are known. For example, U.S. Pat. Nos. 4,482,809, 4,872,980, 5,006,244 and 5,590,390 (all assigned to the assignee of the present invention) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation to inactivate microorganisms present in the fluid.
The devices and systems described in the '809, '980 and '244 patents generally include several UV lamps each of which are mounted within sleeves extending between two support arms of the frames. The frames are immersed into the fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps. One or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like. Since, at higher flow rates, accurate fluid level control is difficult to achieve in gravity fed systems, fluctuations in fluid level are inevitable. Such fluctuations could lead to non-uniform irradiation in the treated fluid.
So-called closed fluid treatment devices are known—see, for example, U.S. Pat. No. 5,504,335 (assigned to the assignee of the present invention). The '335 patent teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source module disposed in the fluid treatment zone. The fluid inlet, the fluid outlet and the fluid treatment zone are in a collinear relationship with respect to one another. The at least one radiation source module comprises a radiation source sealably connected to a leg which is sealably mounted to the housing. The radiation source is disposed substantially parallel to the flow of fluid. The radiation source module is removable through an aperture provided in the housing intermediate to fluid inlet and the fluid outlet thereby obviating the need to physically remove the device for service of the radiation source. A disadvantage with this kind of closed fluid treatment device is that the seal between the radiation source module and the housing must be broken each time the former is to be serviced. This confers additional cost and complexity to the servicing needs of the device.
U.S. Pat. No. 6,500,346 (assigned to the assignee of the present invention) teaches a fluid treatment device, particularly useful for ultraviolet radiation treatment of fluids such as water. The device comprises a housing for receiving a flow of fluid. The housing has a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet and at least one radiation source having a longitudinal axis disposed in the fluid treatment zone substantially transverse to a direction of the flow of fluid through the housing. The fluid inlet, the fluid outlet and the fluid treatment zone are arranged substantially collinearly with respect to one another. The fluid inlet has a first opening having: (i) a cross-sectional area less than a cross-sectional area of the fluid treatment zone, and (ii) a largest diameter substantially parallel to the longitudinal axis of the at least one radiation source assembly.
Many of the above mentioned fluid treatment systems have achieved significant commercial success in the treatment of municipal waste water and/or municipal drinking water.
In certain cases, it would be desirable to have a fluid treatment system for use in treating relatively low volumes of water—e.g., for domestic use, for use in an office environment, etc.
In this regard, reference may be made to:
U.S. Pat. No. 4,179,616,
U.S. Pat. No. 5,471,063 (assigned to the assignee of the present invention),
U.S. Pat. NO. 6,139,726,
U.S. Pat. No. 6,679,068, and
U.S. Pat. No. 6,832,844.
The '063 patent teaches fluid disinfection unit comprising a fluid treatment housing, an electrical supply module and electrical connection means connecting the fluid treatment housing and the electrical supply module. The fluid treatment housing comprises a fluid inlet and a fluid outlet in communication with a reaction chamber, an ultraviolet radiation lamp disposed in the reaction chamber and having a first electrical connector at a first end thereof and a second end thereof being closed. The second end of the ultraviolet radiation lamp is received and held in place by tapered, helical spring. The electrical supply module comprises ballast and which may be removably connected to the ultraviolet radiation lamp and the electrical supply module.
The device taught by the '063 patent has been commercially available from Trojan Technologies Inc. under the tradename Trojan UVMax™ and has achieved commercially success. Notwithstanding this, there is room for improvement.
One of the problems with devices such as those taught by the '063 patent is fluctuation in the environment surrounding the radiation source. This occurs primarily due to the fact that the temperature of the fluid (typically water) surrounding lamp is variable. The variability in temperature can occur to variability of the temperature of the fluid entering the fluid treatment system. Further, the variability of the temperature can occur due to fluid resting in the system when the system is in a non-flowing condition. Since the radiation source is constantly powered, fluid resting in the system will become relatively warmer (i.e., as compared to when fluid is passing through the system) thereby increasing the temperature of the environment around the radiation source.
In recent years, improvements in radiation source (e.g., lamp) technology have developed to the point that radiation sources are designed to operate at an optimum temperature—e.g., for achieving specified disinfection levels and the like. It is important to optimally control the temperature surrounding the radiation source to maintain optimum operation of the radiation source.
Further, over the years, the art has transitioned toward the use of protective sleeves for radiation lamps, wherein the protective sleeves an open end and a closed end thereby facilitating sealing of the radiation lamp—this is particularly important in water submersible systems.
Accordingly, it would be highly desirable to have a fluid treatment system in which the temperature of the environment surrounding the radiation source is relatively constant. More particularly, it would be highly desirable to have a fluid treatment system in which the occurrence of resting fluid described above and fluid temperature fluctuations had little or no effect on the operating temperature of the radiation source.